It is well known to transport photographic material through multi-strand processing apparatus by attaching the material to a transport belt. In these instances, the belt is endless and allows the operators of such apparatus to thread new rolls of material through the apparatus without disturbing or spoiling webs already running.
Multi-strand processing apparatus are used by larger photo-finishers because of their ability to handle more than one roll of material at a time. As rolls finish, new rolls are put on to the apparatus in their place and their leading edge is folded around a clip. This clip has a grip at one end which can be firmly fixed to a moving transport belt to pull the material through the apparatus. When the clip reaches the wind up end of the apparatus, the clip is disengaged and the operator attaches the free end to a wind up core.
The simplest and most common clip relies on the fact that the belt is stiff exerting an outward force on the clip grippers. This has major disadvantages, namely, that is it difficult to attach the clip to the belt, and unclipping is achieved by pushing a wedge between the belt and the clip so that the clip is levered off. Examples of such clips are described in U.S. Pat. Nos. 4,188,108, 4,853,730, 4,821,060, and 4,773,580.
U.S. Pat. No. 4,188,108 describes a clip device which comprises a bar to which photographic material is connected, a hook at one end of the bar for hooking on to a flat conveyor belt, and a resilient clip fixed to the bar at a distance from the hook which clamps on to the conveyor belt. The bar has a slot formed therein for reception of the material and a further clip pivotally attached to the bar is used to retain the material in the slot. In this arrangement, the conveyor belt runs alongside the material to be processed.
U.S. Pat. No. 4,853,730 discloses photographic developing apparatus which has an elastic conveyor belt and at least one clamp which is designed to be mounted on the conveyor belt to engage a strip of photographic material. The clamp has spaced gripping elements which define an opening of width less than that of the conveyor belt and are arranged to engage the marginal portions of the belt. A mechanism for mounting the clamp on the belt is also disclosed.
U.S. Pat. No. 4,821,060 describes another clamp arrangement. A web of photographic material is connected to a running band, which serves to pull the web through processing apparatus, the connection being provided by a clip. One portion of the clip is separably connected to the web and another portion is provided with a channel into which the band is positioned by reducing its effective width.
U.S. Pat. No. 4,773,580 also discloses a clip arrangement which can be coupled to an elastic belt conveyor. The clip has a slotted arm portion into which photographic material is inserted, and a frame portion for receiving the elastic belt. The frame portion is sized so that the belt buckles to reduce its effective width when inserted inside the frame portion.
In all of these clip arrangements, the belt needs to be distorted where a clip is attached to the belt in order to provide the gripping necessary for allowing transport of the material through processing apparatus. This distortion causes the belt to quickly lose its resilience and causes it to crack and possibly break.